Trends in the prevalence, incidence and survival of non-Hodgkin lymphoma subtypes during the 21st century - a Swedish lymphoma register study.

Non-Hodgkin lymphoma (NHL) prognosis has improved in recent years, yet the number of patients living with the diagnosis, i.e. the prevalence, has seldom been reported. The prevalence provides a measure of the burden of disease, useful for healthcare planning and to optimise resource allocation. We provide a systematic presentation of temporal trends in absolute numbers of prevalent patients by NHL subtypes, linking them to trends in incidence, survival and mortality. Patients diagnosed 2000-2016 were identified in the national Swedish lymphoma register. Incidence and mortality rates, relative survival and prevalence were estimated for NHL overall and for major clinical and morphological subtypes. Poisson regression was used to test for temporal trends. Increasing incidence and improved survival have led to a 47% increase in the five-year prevalence of NHL overall in 2016 compared to 2004. An increasing prevalence was observed for all investigated subtypes during the study period, but most notably for diffuse large B cell lymphomas among aggressive subtypes (66%), and marginal zone lymphomas among indolent subtypes (135%). This dramatic increase in NHL prevalence underscores the need to develop and evaluate alternative follow-up schemes to use resources efficiently and still ensure optimal care of lymphoma survivors.